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Investments in parties associated with the reporting entity net of guarantees to be paid by the reporting entity (which are included as liabilities on the balance sheet).

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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AFFILIATIONS, DISCONTINUED OPERATIONS AND RELATED-PARTY TRANSACTIONS - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Feb. 20, 2020	Dec. 31, 2019	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Impairment charges				$ 87,400,000		$ 87,400,000
Investment			$ 36,157,000			36,157,000		$ 106,230,000
Investments in unconsolidated affiliates						(39,800,000)	$ 1,200,000
Notes receivable - affiliate			59,300,000			59,300,000		33,900,000
Net asset - included in investment in affiliates and other noncurrent liabilities			$ 36,200,000			36,200,000		106,200,000
Combined equity contributions and the notes receivable - affiliate						$ 95,500,000		140,100,000
PennEast Pipeline Company, LLC (PennEast)
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			20.00%			20.00%
Contract extension to construct pipeline (in years)	2 years	2 years
Investment			$ 8,000,000			$ 8,000,000		91,300,000
Energenic US LLC
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			50.00%			50.00%
Investment			$ 0			$ 0
Millennium Account Services, LLC
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			50.00%			50.00%
Potato Creek, LLC (Potato Creek)
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			30.00%			30.00%
Equity Method Investee \| REV
Schedule of Equity Method Investments [Line Items]
Related party notes receivable			$ 44,000,000			$ 44,000,000		19,300,000
Secured Debt
Schedule of Equity Method Investments [Line Items]
Related party notes receivable			$ 11,400,000			$ 11,400,000		$ 12,100,000
Interest rate			7.50%			7.50%		7.50%
Unsecured promissory notes
Schedule of Equity Method Investments [Line Items]
Notes receivable - affiliate			$ 3,900,000			$ 3,900,000		$ 2,500,000
South Jersey Energy Company \| EnergyMark
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			33.00%			33.00%
South Jersey Energy Company \| REV
Schedule of Equity Method Investments [Line Items]
Equity interest (as a percent)			35.00%			35.00%
SJRG \| EnergyMark
Schedule of Equity Method Investments [Line Items]
Total operating revenue, affiliates			$ 5,000,000		$ 1,800,000	$ 15,900,000	$ 10,400,000